1. Field of the Invention
The present invention relates to a steering position adjustment device by which a spring for assisting a tilt adjustment operation can be easily and rapidly attached to a fixed bracket and a movable bracket that supports a steering column and is mounted on the fixed bracket to perform a tilting operation.
2. Description of the Related Art
In a conventional steering position adjustment device, a torsion coil spring for constantly biasing a steering column to the upper side of a tilt is disposed between the steering column and an upper bracket for attachment to the vehicle body. The steering column is constantly biased to the upper side of a tilt by the biasing force of the torsion coil spring. Thus, when the steering column is unlocked for tilt adjustment, the steering wheel tends to tilt downward under own weight of the steering column and steering wheel, and by mounting the torsion coil spring, this tilting of the steering wheel side is prevented, and even if the weight of the steering column and steering wheel is large, the driver can easily support the steering wheel by a hand and readily adjust the tilt position.
A large number of torsion coil springs are used in such steering position adjustment devices. A steering position adjustment device of this kind is described in Japanese Patent Application Publication No. 2009-6740. In the general explanation below, the reference numerals used in Japanese Patent Application Publication No. 2009-6740 will be placed in parentheses. The steering position adjustment device is constituted by coil portions (61, 61) disposed on the left and right side, with the axial center of a steering column being disposed therebetween, rearward extending portions (62, 62) extending rearward of the vehicle body from both ends on the inner side of the coil portions (61, 61) (axial center side of the steering column (1)), an abutment portion (63) connecting rear ends of the rearward extending portions (62, 62), and U-shaped hooks (64, 64) formed at both ends on the outer side of the coil portions (61, 61) (side far apart from the axial center of the steering column (1)). Catch portions (39, 39) engaging with hooks (64, 64) of a torsion coil spring (6) are formed to protrude in the direction of withdrawal from the axial center of the steering column (1) at side plates (32A, 32B) of an upper vehicle body attachment bracket (3).
The catch portions (39, 39) have a quadrangular shape, when viewing the upper vehicle body attachment bracket (3) from the lower surface, and U-shaped notch grooves (391, 391) are formed therein. The torsion coil spring (6) in the Japanese Patent Application Publication No. 2009-6740 that has the above-described configuration is assembled by catching the hooks (64, 64) of the torsion coil spring (6) on the notch grooves (391, 391) of the catch portions (39, 39) of the upper vehicle body attachment bracket (3) to obtain a pre-assembled member. The upper vehicle body attachment bracket (3) having the hooks (64, 64) of the torsion coil spring (6) caught thereon, that is, the pre-assembled member, is assembled with the steering column (1) and assembled on the circumference of elongated grooves (33A, 33B) for tilting. At this time, the parts on the circumference of the elongated grooves (33A, 33B) for tilting are assembled, while maintaining the horizontal position of the central axial line of the steering column (1) against the biasing force of the torsion coil spring (6).
The spring (torsion coil spring (6)) is generally assembled by a complex process requiring a large number of manual operations. Further, the torsion coil spring plays a role of biasing the steering column and steering wheel upward, the elastic force is strong, a large force acting against the biasing force of the torsion coil spring (6) is necessary to assembly the torsion coil spring (6) and a load on the worker is large. Where the elastic force of the torsion coil spring (6) is decreased to reduce the load of the worker, the torsion coil spring (6) can easily slip out of the U-shaped notch groove (391).
Further, the assembling on the circumference of the elongated grooves (33A, 33B) for tilting should be performed, while maintaining the steering column (1) in a substantially horizontal state against the biasing force of the torsion coil spring (6), which requires the worker to apply a large force. Since the worker is required to apply continuously a force acting against the biasing force of the torsion coil spring (6) through the entire assembling operation, a load on the worker is very high. Accordingly, an object to be attained (a technical problem to be resolved) by the present invention is to enable easy and fast assembling of the torsion coil spring with the fixed bracket and movable bracket even through the elastic force of the torsion coil spring is strong.